Bulletin of the Sea Fisheries Institute 2 (156) 2002 - CEEMaR

More documents

Recommendations

Info

$C:\Documents and Settings\admin - CEEMaR$




Sexual maturation of mackerel icefish ..... 23 contribution of mature fish 1,00 a) 0,50 0,00 10 15 20 25 30 35 40 45 50 55 60 length [ cm ] 18 16 14 b) 12 10 8 [ % ] 6 4 2 0 10 15 20 25 30 35 40 45 50 55 60 length [ cm ] contribution of mature fish 1,00 0,50 0,00 10 15 20 25 30 35 40 45 50 55 60 length [ cm ] 18 16 14 12 10 8 [ % ] Fig. 6. Sexual maturity (a) and length distribution (b) curves of C. gunnari from South Shetland Island. a) b) 6 4 2 0 10 15 20 25 30 35 40 45 50 55 60 length [ cm ] males females males females Fig. 7. Sexual maturity (a) and length distribution (b) curves of C. gunnari from the Kerguelen Islands. 2 0
24 JÓZEF SOSIÑSKI and KORDIAN TRELLA L 50 [cm] 35 30 25 males y = -0.078x + 25.513 r = 0.17 20 15 females y = -0.2651x + 24.639 r = 0.51 10 76/77 77/78 78/79 80/81 81/82 83/84 84/85 85/86 86/87 87/88 88/89 90/91 92/93 seasons males Liniowy (males) females Liniowy (females) Fig. 8. L 50 length of the C. gunnari stock from South Georgia Island in subsequent seasons of the study. maturation is achieved. L max was accepted as the length of the largest specimens in a given stock (Table 2). The L 50 to L max ratio for both for males and females (39.2 and 34.9, respectively) was the lowest in the fishing ground near South Georgia. It was higher in other stocks and varied from 47.2 to 65.8 (Table 2). In order to analyze the annual spawning maturation cycle, mature specimens with gonads in stages II-V were selected and considered to be 100%. Then the percentages of fish in particular stages were compared. The results are presented in Table 3. Data for particular months at different fishing grounds are the averages from different seasons of the studies. The gonads of the specimens studied were most frequently in stage II. During the Antarctic summer and autumn (January-April), the percentage of fish with gonads in stage III increased. This is especially apparent in the stock from South Georgia, where the greatest number of studies over a relatively long period of time were conducted. A relatively small number of mature fish (gonad stage IV) and spent fish (gonad stage V) were observed. Figure 9 presents the average degree of gonad maturity for sexually mature fish (gonad stages II-V) by month. In the majority of the stocks investigated, study material was collected only during a few months of the year. As mentioned above, the most representative material was collected in the fishing grounds of South Georgia. Figure 9 presents the plot of the annual maturation cycle of the stock in this location, and it indicates that the average degree of maturity of both sexes increases in the Antarctic summer and fall. The study material that was collected facilitated the analysis of the annual maturation cycle with respect to fish sex and size, with the assumption that specimens smaller than L 95 (27.6 cm for males and 24.0 cm for females) are usually spawning for the first time while specimens larger than L 95 are spawning for a subsequent time (Fig. 10).
Page 1 and 2: ISSN 1429-2335 Bulletin of the Sea
Page 3 and 4: 4 WIES£AW BLADY, JAN NETZEL and JA
Page 9 and 10: 20 23 26 29 32 35 38 41 44 47 50 53
Page 11 and 12: 12 WIES£AW BLADY, JAN NETZEL and J
Page 13 and 14: 14 WIES£AW BLADY, JAN NETZEL and J
Page 15 and 16: 16 JÓZEF SOSIÑSKI and KORDIAN TRE
Page 21: 22 JÓZEF SOSIÑSKI and KORDIAN TRE
Page 33 and 34: 34 VIDA ŽILIUKIENE The fish fauna
Page 35 and 36: 36 VIDA ŽILIUKIENE Table 1. The ex
Page 37 and 38: 38 VIDA ŽILIUKIENE 1997.06.03 1999
Page 39 and 40: 40 VIDA ŽILIUKIENE Frequency [%] F
Page 41 and 42: 42 VIDA ŽILIUKIENE REFERENCES Anne
Page 43 and 44: BULLETIN OF THE SEA FISHERIES INSTI
Page 45 and 46: Morphomechanic changes during embry
Page 55 and 56: BULLETIN OF THE SEA FISHERIES INSTI
Page 57 and 58: Variability of sprat peak spawning
Page 67 and 68: 70 JÓZEF SOSIÑSKI AND ANDRZEJ KOM
Page 73 and 74:
76 JÓZEF SOSIÑSKI AND ANDRZEJ KOM
Page 75 and 76:
78 JÓZEF SOSIÑSKI AND ANDRZEJ KOM
Page 77 and 78:
WSKAZÓWKI DLA AUTORÓW INFORMACJE
show all

Bulletin of the Sea Fisheries Institute 2 (156) 2002 - CEEMaR

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?